Publish executable Rust and C/C++ integration guides

[GeneralPawz]

What

Document the supported v0.4 consumption paths with copy-pasteable, CI-executed examples for narrow Rust crates, the Rust facade, plain C, and C++/CMake. Include a decision table for selecting a profile and an honest capability/refusal matrix.

Why now

A downstream boundary is not usable if consumers must read workspace manifests or provider implementations to assemble it. Documentation must lead users to the tested public path and make unsupported geometry obvious before deployment.

Definition of done

• Each supported integration profile has an executable quickstart pinned to an immutable release.
• Examples explain feature selection, provider selection, units, tolerance, ownership, errors, threading, and deterministic behavior.
• Native examples cover header discovery, linking, runtime library placement, ABI-version checks, and destruction of every owned handle.
• The capability matrix distinguishes exact output, mesh output, approximation, and typed refusal.
• The roadmap and release documentation reflect the inserted v0.4 integration milestone and renumbered v0.5/v0.6 milestones.
• Documentation examples are sourced from or checked by the black-box consumer probes.

Non-goals

No example claims production support for operations that lack executable evidence.

Area

docs

Effort

Medium